Beta-(B)- agonists act via B2 adrenergic receptors (B2AR) in the treatment of asthma to relax bronchial smooth muscle. Effects of B- agonists on other lung cells which express B2AR and their role in asthma is not clear. In this project lung cells are obtained by bronchoscopy to test signal transduction characteristics and answer: Is there an intrinsic defect in B2AR signal transduction in asthma patients' lung cells? Does B-agonist therapy induce desensitization of lung cell B2AR? Do B2AR polymorphisms contribute to signal transduction defects?